Tell me what you're looking for specifically and I *probably* can tell you where to find it...

My most frequent low carb purchases are made at:
Vitamin shoppe- cheapest atkins and keto products
TJ Maxx or Porto Ricco Importing Co. for Davinci's Syrups
Health Nuts Health food stores for everything else (la tortillas, todd's bagels etc. etc.)

Let me know if you have anything specific you'd love to find

It depends where in Brooklyn you will be. If you're anywhere near a Key Food (supermarket), I have noticed lately that they have been increasing their supplies of low carb packaged food (including Arnold lower carb bread and Atkins products). I can give you more specific info if you'll be near Brooklyn Heights, Cobble Hill (LIU Hospital) or Park Slope (Methodist Hospital).

In Manhattan, Willner Chemists (one on Broadway and Murray St. across from city hall, and one on Park Ave. and 41st St.) recently set up a whole low carb section (at least the one on Park/41st).

There's always an abundance of produce stands around. Also a vegetable delivery service called Urban Organic (you can specify no fruit, no potatoes, etc.) that's based in Brooklyn.

I agree with Ariana that the Vitamin Shoppe and Health Nuts are good resources, too.

Mil